How Email Marketing Works
Email marketing begins with list building: collecting email addresses from prospective and existing customers through website sign-up forms, lead magnets, checkout flows, and event registrations. Subscribers opt in to receive communications, which distinguishes email from purchased list campaigns and improves deliverability by reducing spam complaints.
Messages are sent through an email service provider (ESP) such as Mailchimp, HubSpot, Klaviyo, or ActiveCampaign. ESPs manage subscriber lists, provide templates, track performance metrics, and handle the technical requirements for reliable inbox delivery including authentication protocols such as SPF, DKIM, and DMARC. Choosing an ESP with strong deliverability infrastructure is a foundational decision that affects whether emails reach inboxes or land in spam folders.
Types of Email Campaigns
Email programs typically include several distinct campaign types. Broadcast campaigns (also called newsletters or one-to-many sends) go to a segment or the entire list on a scheduled basis. They may contain curated content, product announcements, or promotional offers. Welcome sequences are automated series triggered when a new subscriber joins the list, designed to introduce the brand and set expectations for future communications.
Nurture sequences guide prospects through the buying journey by delivering relevant content at each stage of consideration. They are triggered by behavior such as downloading a resource, attending a webinar, or visiting a pricing page. Transactional emails are sent in response to specific user actions, including purchase confirmations, shipping notifications, and password resets. Abandoned cart emails, a subcategory of behavioral emails, re-engage users who added items to a cart but did not complete a purchase and are among the highest-converting messages in e-commerce programs.
Key Email Marketing Metrics
Open rate measures the percentage of delivered emails that were opened by the recipient. Following Apple’s Mail Privacy Protection changes, open rates have become less reliable as a standalone metric because pre-loading inflates reported opens. Click-through rate (CTR) measures the percentage of recipients who clicked at least one link in the email and remains a more reliable indicator of engagement. Click-to-open rate (CTOR) divides clicks by opens to measure how compelling the email content is among those who opened it.
Conversion rate tracks the percentage of recipients who completed a desired action, such as making a purchase or filling out a form. Unsubscribe rate and spam complaint rate are health metrics: consistently elevated unsubscribe rates signal that content is misaligned with audience expectations, while high complaint rates damage sender reputation and deliverability. List growth rate measures whether the subscriber base is expanding or contracting after accounting for unsubscribes and new opt-ins.
Segmentation and Personalization
Segmentation divides a subscriber list into subgroups based on shared characteristics, allowing marketers to send more relevant messages. Common segmentation variables include geographic location, purchase history, engagement level (active vs. inactive subscribers), and stage in the buyer journey. Personalization extends segmentation by using individual-level data to customize message content, such as addressing recipients by name or recommending products based on past behavior. Programs that combine meaningful segmentation with behavioral personalization consistently outperform batch-and-blast sends on open rate, click rate, and revenue per email.
Email Deliverability
Deliverability is the foundation of email program performance. A message that is not delivered cannot be opened, clicked, or converted. Deliverability is determined by sender reputation, which is scored by internet service providers and inbox providers based on complaint rates, bounce rates, engagement levels, and authentication status. Senders with strong reputations consistently reach the primary inbox. Senders with poor reputations see messages routed to spam folders or blocked entirely.
Maintaining deliverability requires ongoing list hygiene: removing hard bounces after every send, suppressing chronically unengaged subscribers, and honoring unsubscribe requests promptly. Warming a new sending domain gradually by starting with small volumes sent to the most engaged subscribers establishes positive sender reputation before scaling to the full list. ESPs that monitor bounce and complaint rates automatically and alert marketers when thresholds are exceeded help teams identify and address deliverability problems before they become severe.
Sources
- Litmus. (2024). State of Email Report. Litmus Software Inc. https://www.litmus.com/state-of-email
- Mailchimp. (2024). Email Marketing Benchmarks and Statistics by Industry. Intuit Mailchimp. https://mailchimp.com/resources/email-marketing-benchmarks/
- Campaign Monitor. (2024). Email Marketing Benchmarks. Marigold. https://www.campaignmonitor.com/resources/guides/email-marketing-benchmarks/
- HubSpot Research. (2024). The State of Marketing Report. HubSpot Inc. https://www.hubspot.com/state-of-marketing
- Data and Marketing Association. (2023). Email Marketing Industry Census. DMA. https://dma.org.uk/research
- Apple Inc. (2021). Mail Privacy Protection. Apple Newsroom. https://www.apple.com/newsroom/2021/06/apple-advances-its-privacy-leadership-with-ios-15-ipados-15-macos-monterey-and-watchos-8/
- Salesforce. (2024). State of the Connected Customer. Salesforce Inc. https://www.salesforce.com/eu/resources/research-reports/state-of-the-connected-customer/
- Klaviyo. (2024). Email and SMS Benchmarks. Klaviyo Inc. https://www.klaviyo.com/marketing-resources/benchmark-report-2024
- Really Good Emails. (2024). Email Design Best Practices. Really Good Emails. https://reallygoodemails.com
- Returnpath / Validity. (2024). Deliverability Benchmark Report. Validity Inc. https://www.validity.com/resource-center/2025-email-deliverability-benchmark-report/
Written by the My Marketing File editorial team. Updated June 2024.